Big theory update

Change log

• Section 1.2 "Definitions" added
• Section 1.4 "Sync methods in parallel programming" added
• Section 3.5 "Errors in parallel programs" updated:
  • Race conditions added
  • ABA problem added
  • Priority inversion added
  • Starvation added
  • False sharing added
• Lab from 2 to 5 updated
• Bibliography added
• Some images updated
• Size of table of contents increased
• And other small fixes 🌝